This invention relates to an internal combustion engine driven generator in which a capacitor excitation type synchronous generator is driven by an internal combustion engine.
In an internal combustion engine employed for a generator of this type, control is so made that the internal combustion engine provides its rated output when the revolution per minute (rpm) of the generator is its rated one and that the revolution per minute of the engine is maintained as constant as possible by the governor when a load applied thereto is relatively light. However, practically, the revolution per minute is increased by 4 to 10% with no load. Accordingly, heretofore it is necessary to provide an automatic voltage regulator for the generator to suppress the increase of the output voltage attributed to the increase of speed which is caused when the load is relatively light. Thus, the method is disadvantageous in that the device is necessarily intricate in construction and accordingly high in manufacturing cost.